“Do you know what the most fascinating thing about February is? Of course, it is not Valentine’s week, but the month gaining a day more than usual, i.e., 29th Feb. And why is it important that it repeats only every 4 years?”. Leap year science is something that never fails to amaze people, but many times we don’t understand the science behind it. Leap years are celebrated for a long time, but who introduced it to us, and on what basis is it being followed through all these years? Is leap-year science valid? Let’s understand the logic behind adding a day more.
A leap year is a year in which there are 366 days instead of 365 days like a normal year. An extra day present is responsible for synchronization between the astronomical year and our calendar. An astronomical year represents all the astronomical events that would be taking place in that year, and since they don’t repeat, an extra day is added so as not to have any drift in the dates. The concept of the leap year was introduced by Julius Caesar in 45 B.C., and many calendars have different concepts surrounding it.
History of leap year science?
Image of Julian Calendar formed by Julius CaesarJulian calendar: Julius’s concept of leap year science was elementary; his rule was to add a day after every four years, and his algorithm was approximately the same, but however, it still wasn’t precise. Despite the lack of precision, the Julian calendar was followed for the next 1600 years, until the Catholic Church explained the phenomena of the March Equinox, which weren’t considered earlier, which is now present in the Gregorian calendar. Due to this, the algorithm of the Julian calendar showed 365.25 days, whereas the earth’s tropical year had 365.2425 days.
Gregorian calendar: The Gregorian calendar is the one we follow in today’s time, and it is said to be the most precise of all the calendars. When the number of days in the Gregorian calendar was calculated, it came out to around 365.2422 days, which is approximately the same as the Earth’s tropical year’s calculation.
Baha’i calendar: The calendar, like others, is also dependent on the Sun, but unlike other calendars, it consists of 19 months instead of 12 months, each month consisting of 19 days. Hence the year is composed of a total of 361 days; the year starts on the 21st of March; it usually has 4 days, but at times an extra day is added to ensure that the year starts from the March equinox.
Hindu Calendar classified through NakshatrasHindu calendar: It refers to a Vedic calendar, which is a lunisolar calendar, meaning it uses lunar months and a solar year. Confusing, right? But it is extremely straightforward, as the solar year has 11 days more than the lunar year; that being the scenario, a whole extra lunar month is added every five years. Another example of the lunar calendar is the Jewish calendar and instead of adding an extra month each month had alternating days between 29 and 30 days.
There are more calendars than the above-mentioned one, developed on different religious beliefs, like Islamic, Hebrew, and many more.
How are leap years calculated?
Calculating a leap year is very simple once you understand whether it is the end of a century or not. If the year that you are considering is divisible by 4, then it is a leap year, but if it is the end of a century, as in years like 1800, 1900, 2000, etc., then they should be divisible by 400; only then are they classified as leap years.
Why do leap years exist?
The unique concept of leap year science exists to maintain the synchronization between the calendar that we follow and the Earth’s orbit around the sun so that the dates of astronomical events are not shifted. It is also responsible for maintaining seasons, and it ensures that the seasons won’t shift with time. Earth is believed to orbit around the sun in a time frame of 365 days, but it isn’t true; Earth takes some extra time i.e. (0.25 days extra on astronomical timeline), and to balance that out, a leap day is added.
Why do we have a leap year after every four years?
The difference in orbital period for a Tropical year, Common year and Leap year Credits: timeanddate
The leap year science is another concept that makes life unique, other than all the mind-boggling facts; ever wondered why leap year only occurs after 4 years and not after 3 or 5 years? The reason for this is the number of days Earth orbits around the sun. The earth orbits around the sun in 365.2422 days; to be precise, due to the extra quarter day, an extra day is added to balance it out and not cause any issues.
What would happen if there were no leap years?
If a leap year hadn’t been introduced, then we wouldn’t have seasons as we have now. The seasons would shift by a day every four years and wouldn’t be as constant as they are now, which would cause a lot of problems for us to keep track of major events. Leap years not only exist so as to not cause any shifting in seasons but they ensure that phenomena like equinoxes and solstices wouldn’t occur at different times. Not only the life on Earth is affected, but astronomers will also face major obstacles in tracking celestial objects.
Equinoxes and Solstices
Think if for the previous five hundred years there was no leap year. Then we would have been lagging approximately 125 days (for every 100 years we will have 25 leap years) with the seasonal changes and track of other astronomical events. So think if we hadn’t added a single day every four years what season would have been now??
Leap year science is definitely one of the most niche phenomena that is repeated every four years, and yet we don’t know the reason behind its occurrence. Leap years are not just one of a kind because they have an extra day, but the sole reason for them being one of a kind is that it showcase that the imperfections of the human calendar year of the earth’s orbit around the sun lead to the occurrence of such a magnificent phenomenon.